Objective:To investigate the relationship between serum levels of cystatin C and severity of coronary heart disease(CHD). Methods:Five hundred and twenty-five patients with CHD who underwent coronary angiography were selected in the study.The relationship between serum levels of cystatin C and the pathogenetic condition of CHD,the number of diseased vessels and the CHD Gensini cumulative index was evaluated. Serum levels of cystatin C was measured by nephelometric immunoassay. All data were analyzed by univariate and multivariate analyses. Results:①With the increase of serum levels of cystatin C,the pathogenetic condition in patients with CHD became more serious,the number of diseased vessels and the CHD Gensini cumulative index increased.Due to the reaction at the acute phase of acute myocardial infarction(AMI),the serum levels of cystatin C decreased;②Further logistic regression analysis indicated that cystatin C had significant correlation with pathological changes of coronary artery(OR was 5.346,95% CI = 2.225~12.846,P < 0.01);③After adjusting the influencing factors such as age,sex and so on,multivariable stepwise regression analysis showed that cystatin C also had significant correlation with the CHD Gensini cumulative index(β = 0.149,P < 0.01). Conclusion:The serum levels of cystatin C had significant correlations with CHD.With the increase of serum levels of cystatin C,the pathogenetic condition and pathological changes of coronary artery in patients with CHD became more and more serious.